The present invention relates to an input transformer for a television receiver provided between a feeder line extending from an antenna and a tuner and, more particularly, to an arrangement of the input transformer including an unbalanced signal suppress transformer for suppressing unbalanced signal transmitted from the feeder line and an impedance transformer for dropping the impedance.
Generally, the unbalanced signal is produced when one of a pair of lead wires constituting the feeder line carries a reflected signal from a television receiver due to a deformation of a symmetric characteristic of the feeder line. The reflected signal is often caught from a rod type antenna which is located adjacent the television receiver.
Referring to FIG. 1, there is shown a general block diagram of the input transformer connected between an antenna 2 and a tuner 8. A pair of output terminals 2a and 2b of the rod type antenna 2 is connected through a feeder line 3, including a pair of lead wires 3a and 3b, to an unbalanced signal suppress transformer 4. An impedance transformer 6 for dropping the impedance from 300.OMEGA. to 75.OMEGA. is connected between the unbalanced signal suppress transformer 4 and the tuner 8.
Conventionally, these two transformers 4 and 6 are prepared by two independent and different types of transformers which are, as shown in FIG. 2, a balanced type transformer for the unbalanced signal suppress transformer 4 and an unbalanced type transformer for the impedance transformer 6, each having its own transformer core. As shown in FIG. 2, the unbalanced signal suppress transformer or balanced type transformer 4 includes first and second coils 10 and 12 which are wound on a first half side of a core having a shape similar to a symbol .infin. which is hereinafter referred to as a spectacles frame shaped core and third and fourth coils 14 and 16 which are wound on the second half side of the spectacles frame shaped core. Similarly, the impedance transformer or unbalanced type transformer 6 includes first and second coils 18 and 20 wound on a first half side of another spectacles frame shaped core and third and fourth coils 22 and 24 wound on the second half side of said another spectacles frame shaped core.
However, since these two transformers 4 and 6 are in a close relation to each other in terms of their function in the television receiver, it is preferable to arrange these two transformers 4 and 6 in one unit employing one core for the unbalanced signal suppress transformer 4 and for the impedance transformer 6.
Furthermore, it is preferable to simplify these transformers 4 and 6 by reducing the number of coils employed therein.